The presence of significant quantities of H.sub.2 S in various "sour" industrial gaseous streams poses a persistent problem. Although various procedures have been developed to remove and recover this contaminant, most such processes are deficient, for a variety of reasons.
While sour gaseous streams that contain relatively low concentrations of H.sub.2 S may be treated successfully in a variety of ways if deep removal, e.g., greater than 95 percent removal of H.sub.2 S, is not required, removal of this level, or greater, demands efficiencies of operation if excessive costs of operations and materials are not to be incurred.
One scheme for carrying out the gas treatment utilizes a two-stage contacting procedure in which a venturi-shaped contacting zone is utilized as an initial or primary contacting stage to remove the bulk of the H.sub.2 S, and follow-up or "clean-up" stage, such as a packed column or sparged tower, is provided for removing the remainder of the H.sub.2 S in the gaseous stream. This configuration has a number of drawbacks, such as susceptibility of plugging, high gas pressure drop, and high cost. Again, U.S. Pat. No. 4,238,462 describes a process for reacting in circulating reaction solution with different gases in a single reaction vessel, the movement of the solution being accomplished by contrived density differential in the different reaction zones of the vessel. While this process has the advantage of "free" liquid circulation, it appears limited to treatment of gases where the regenerating oxygen does not pose a hazard, and thus appears unsuited, e.g., to treatement of hydrocarbons such as methane or ethane.
Accordingly, a process which provided an efficient and economic contacting technique to insure good absorption and reaction rates of the H.sub.2 S into and with the contacting solution, while avoiding or minimizing the deficiencies mentioned, might have great utility. The invention is directed to such a process.